1. Field
The present disclosure relates to a differential pressure water electrolysis system.
2. Description of the Related Art
Hydrogen gas is used as a fuel gas for a fuel cell to generate electricity, for example. A water electrolyzer is typically employed when producing hydrogen gas. The water electrolyzer uses a solid polymer electrolyte membrane for generating hydrogen (and oxygen) through electrolysis of water. An electrode catalyst layer is provided on both surfaces of the solid polymer electrolyte membrane such that an electrolyte membrane-electrode structure is configured, and a feed conductor is disposed on both sides of the electrolyte membrane-electrode structure such that a unit is configured.
While in a state in which a plurality of units are stacked, voltage is applied to both ends in the stacking direction and water is supplied to an anode feed conductor. Accordingly, water is electrolyzed and hydrogen ions (protons) are generated on the anode side of the electrolyte membrane-electrode structure, the hydrogen ions permeate the solid polymer electrolyte membrane and move to the cathode side, and the hydrogen ions are combined with the electrons such that hydrogen is produced. Meanwhile, on the anode side, oxygen that has been generated together with hydrogen is discharged from the unit along with surplus water.
In the above type of water electrolyzer, they are cases in which a high pressure water electrolyzer (a differential pressure water electrolysis system) that produces, by electrolyzing water, oxygen and hydrogen that has a pressure that is higher than that of the oxygen is employed. In such a case, a disk spring (an elastic member), for example, is used as a compression member on the cathode side on which high pressure hydrogen is generated while the disk spring constitutes a conduction passage. Accordingly, the contact area between the components that configure the conduction passage may disadvantageously become small disadvantageously causing the components to be deteriorated easily.
A high pressure water electrolyzer disclosed in Japanese Unexamined Patent Application Publication No. 2012-87403, for example, is known. The above high pressure water electrolyzer includes a conductive sheet that is integrally interposed across a portion between a cathode separator and an elastic member to a portion between a plate member and a cathode feed conductor and that includes a conduction passage that electrically connects the cathode separator to the cathode feed conductor.